The real time measurement of mass fluid flow, both liquids and gasses, in pipes and conduits is an important and oftentimes critical capability in innumerable commercial and industrial processes, environmental control apparatus, energy supply systems and municipal infrastructure, to name only the more important. Mass flow measurements have taken on particular significance with the rapidly increasing concern for determining the thermal flow of heating and cooling fluids.
Due to this critical necessity, several types of mass flow meters have been developed over the years which exhibit certain characteristics which render them especially suitable for certain applications. One of the least complex types comprehends a calibrated tube which tapers (narrows) downwardly, carries upwardly directed flow and includes a float. As flow increases, the float rises providing a visual indication of the present flow rate.
A more complex flow meter includes a turbine rotor disposed in a pipe, preferably at a distance downstream of turbulence inducing features such as corners and valves. A sensor mounted in the pipe proximate the turbine rotor senses its rotation and provides a signal to associated equipment which may provide current flow or which may be integrated to provide accumulated flow.
A third type of flow sensor having somewhat limited application utilizes Venturi nozzles or throats. In these devices, the difference in pressure at pressure taps before and at the Venturi constriction are utilized to calculate fluid flow.
A related, less complicated device is an orifice plate. Pressure readings are taken upstream and downstream of the orifice plate from which flow may be adduced. While it is generally accepted that orifice plate flow readings are accurate when the plate is new, wear or damage to the orifice can significantly and adversely affect its accuracy.
Thus, while current flow meters generally achieve their intended purpose, there is a need for a new and improved device having greater accuracy, application flexibility and durability.